Department of Experimental Medical Science, Lund University, Lund, Sweden.
LINXS-Lund Institute of Advanced Neutron and X-ray Science, Lund, Sweden.
Nat Commun. 2023 Feb 3;14(1):600. doi: 10.1038/s41467-023-36272-y.
Aquaglyceroporin 7 (AQP7) facilitates glycerol flux across the plasma membrane with a critical physiological role linked to metabolism, obesity, and associated diseases. Here, we present the single-particle cryo-EM structure of AQP7 determined at 2.55 Å resolution adopting two adhering tetramers, stabilized by extracellularly exposed loops, in a configuration like that of the well-characterized interaction of AQP0 tetramers. The central pore, in-between the four monomers, displays well-defined densities restricted by two leucine filters. Gas chromatography mass spectrometry (GC/MS) results show that the AQP7 sample contains glycerol 3-phosphate (Gro3P), which is compatible with the identified features in the central pore. AQP7 is shown to be highly expressed in human pancreatic α- and β- cells suggesting that the identified AQP7 octamer assembly, in addition to its function as glycerol channel, may serve as junction proteins within the endocrine pancreas.
水甘油通道蛋白 7（AQP7）促进甘油穿过质膜的流动，其关键生理作用与代谢、肥胖和相关疾病有关。在这里，我们展示了在 2.55Å分辨率下确定的 AQP7 的单颗粒冷冻电镜结构，采用了两个附着的四聚体，通过细胞外暴露的环稳定，其构象类似于 AQP0 四聚体的特征相互作用。在四个单体之间的中央孔显示出由两个亮氨酸过滤器限制的定义明确的密度。气相色谱-质谱（GC/MS）结果表明，AQP7 样品中含有甘油 3-磷酸（Gro3P），这与中央孔中鉴定的特征一致。AQP7 在人胰腺α-和β-细胞中高度表达，表明鉴定的 AQP7 八聚体组装除了作为甘油通道的功能外，还可能作为内分泌胰腺中的连接蛋白。
